Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (“CDMA”) systems, time division multiple access (“TDMA”) systems, frequency division multiple access (“FDMA”) systems, 3GPP Long Term Evolution (“LTE”) systems, and orthogonal frequency division multiple access (“OFDMA”) systems.
Generally, a wireless multiple-access communication system can simultaneously support communications for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communications link from the base stations to the terminals, and the reverse link (or uplink) refers to the communications link from the terminals to the base stations. This communications link may be established via a single-in-single-out, multiple-in-signal-out, or a multiple-in-multiple-out (“MIMO”) system.
Generally, wireless cellular communication networks incorporate a number of mobile user equipments (“UEs”) and a number of base nodes (“NodeBs”). A NodeB is generally a fixed station, and may also be called a base transceiver system (“BTS”), an access point (“AP”), a base station (“BS”), or some other equivalent terminology. As improvements to networks are made, the NodeB functionality has evolved, so a NodeB is sometimes also referred to as an evolved NodeB (“eNB”). In general, NodeB hardware, when deployed, is fixed and stationary, while UE hardware is portable.
In contrast to a NodeB, a mobile UE can comprise portable hardware. A UE, also commonly referred to as a terminal or a mobile station, may be a fixed or mobile device, and may be a wireless device, a cellular phone, a personal digital assistant (“PDA”), a wireless modem card, and so on. Uplink communication (“UL”) refers to a communication from a mobile UE to a NodeB, whereas downlink (“DL”) refers to a communication from a NodeB to a mobile UE.
Each NodeB contains radio frequency transmitter(s) and the receiver(s) used to communicate directly with the mobile UEs, which move freely around it. Similarly, each mobile UE contains radio frequency transmitter(s) and receiver(s) used to communicate directly with a NodeB. In cellular networks, the mobile UEs cannot communicate directly with each other but have to communicate with the NodeB.
Relay Nodes (“RNs”) have been considered for use in a wireless communication system. A RN may be located between terminals, UEs, and base stations, such as eNBs, to provide range extension, increase data rates, facilitate UE mobility, improve cell edge coverage, as well as providing other functions. Different types of RNs may be implemented, including, for example, a “Type 1” RN, which refers to an RN that appears as an independent NodeB to a UE. As such, a Type 1 RN can transmit its own synchronization channels, control channels, and so on.
Further, an in-band half-duplex RN which is not able to transmit and receive on the same band at the same time, may be supported by a wireless communication system. It is currently appreciated that Multimedia Broadcast over a Single Frequency Network (“MBSFN”) intervals can be used in order to create “blank periods” in which to receive DL communications from a donor NodeB on the backhaul link. However, due to the nature of MBSFN subframes (e.g., they contain PDCCH transmissions lasting one or two OFDM symbols), it is appreciated that the RN can in some cases be unable to listen to PDCCH transmissions from the donor NodeB. As a result, one or more relay control channels (e.g., R-PDCCH, R-PHICH, P-PCFICH, etc.) can be implemented between a NodeB and an RN. The present application therefore addresses various aspects related to the design of a relay backhaul channel.